In this study, an experimental rat ligated heart model was used to observe the effect of treatment with carvedilol, metoprolol and metoprolol plus a highly selective a,adrenergic blocking agent, bunazosin, after acute myocardial infarction. (MI). Compared with an untreated MI group, all drug-treated groups demonstrated attenuation of inflammatory mediators, activation of nuclear factor-kappa B (NF-kappa B), and increased levels of mRNA and active protein for the collagenases matrix metallopeptidase (MMP)-8 and MMP-13 in the non-infarct zone of the ventricle, as well as inhibition of the increase of left ventricular end-diastolic pressure. Supplementation of metoprolol with bunazosin did not add greatly to the effects of metoprolol alone. Of the three drug treatments, carvedilol showed a uniquely potent antioxidant activity that may strengthen its capacity to inhibit oxidative stress, the release of inflammatory mediators and activation of NF-kappa B. This study may help provide a mechanistic explanation for the greater benefits shown by carvedilol compared with metoprolol in treating heart failure.

Zhuang, X. F.,et al."Distinctive Effects of Carvedilol in the Non-infarct Zone: Remodelling of the Ligated Rat Heart Linked to Oxidative Stress".JOURNAL OF INTERNATIONAL MEDICAL RESEARCH 37.5(2009):1354-1364.